•26. HALORAGIACE.E. 377 



extreme forms this one and Liitetiana are readily distin- 

 guishable, and aj^pear as much like permanent species as 

 do many other pairs of allied species ; but when the ' in- 

 termedia' is placed between them, it becomes extremely 

 difficult to specify or find any strong distinction ; the two 

 extremes being so nearly connected by the intermediate 

 variety, that all clear distinctions cease. The occasional 

 perfection of one cell in the fruit of C. alpina, seems an 

 insufficient character ; both cells being usually abortive 

 or obsolete. 



/>!</^.V^^^ 379. HiPPURis VULGARIS, Linn. 



Area 1 2 3 4 5 6^ 8 9 10 11 12 13 14 15 16 * IS. 



South limit in Dorset, Isle of Wight, Kent. /^*«- -^"^ 



North limit in Shetland, Orkney, Hebrides. 

 I Estimate of provinces 18. Estimate of counties 70. 



Latitude 50 — 61. British type of distribution. 



Agrarian region. Inferagrarian — Superagrarian zones. 



Descends to the coast level, in the Channel. 



Ascends to 100 or 200 yards, in England. 



Range of mean annual temperature 50 — 46. 



Native. Lacustral or Paludal. Not a common species, 

 although widely distributed. Apparently very scarce and 

 local in the Peninsula ; and still unrecorded from North 

 Wales and the North Highlands ; although the probabi- 

 lity of its occurrence in those provinces seems strong 

 enough to warrant their inclusion in the provincial esti- 



mate. 



^//. //V / Aj 380. Myriophyllum verticillatum, Linn. 



Area 12345*789 10 11****** [18]. 

 South limit in Dorset, Sussex, Kent. CcA^^f^/f^^c 



3 c 



